Positron Emission Tomography (PET) has now reached a degree of maturity where several of its early promises have been fulfilled. PET is able to provide information on both structure and function of different parts of the brain. It is becoming an important fundamental tool for both clinical diagnosis and medical research. Presently, PET performance is limited by the photosensors used. Future advances in PET system technology can only come about by performing research to improve the capabilities of the gamma ray detectors. Early results with indium iodide (bandgap 2.01eV) as a photon sensor are very encouraging and further research into this promising material has a high probability of producing a new detector technology with better performance which could be the basis for a future generation of PET instruments. The goal of this Phase I program is to demonstrate the feasibility of using this semiconductor to make this approach work.